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  Photoelectric transducer and its manufacturing methodUSPTO Application #: 20070194311Title: Photoelectric transducer and its manufacturing method Abstract: A photoelectric transducer comprises an electrode (5) on which a semiconductor layer (7) carrying a sensitizing dye is deposited. The semiconductor layer (7) contains semiconductor particles and a binder and has a porosity of 40 to 80%. A method for manufacturing a photoelectric transducer by applying a solution containing semiconductor particles and a binder to an electrode (5), drying the electrode, and pressing the electrode under a pressure of 20 to 200 Mpa so as to form a semiconductor layer (7) is also disclosed. By the method, a photoelectric transducer comprising a semiconductor layer where a conduction path of photo-excited electrons is ensured without sintering the semiconductor layer at a high temperature and which has an adhesive power adaptable to the flexibility of the base and exhibiting excellent photoelectric transducing characteristics can be provided. (end of abstract) Agent: Osha Liang L.L.P. - Houston, TX, US Inventors: Katsunori Kojima, Teruhisa Miyata USPTO Applicaton #: 20070194311 - Class: 257057000 (USPTO) Related Patent Categories: Active Solid-state Devices (e.g., Transistors, Solid-state Diodes), Non-single Crystal, Or Recrystallized, Semiconductor Material Forms Part Of Active Junction (including Field-induced Active Junction), Amorphous Semiconductor Material, Field Effect Device In Amorphous Semiconductor Material The Patent Description & Claims data below is from USPTO Patent Application 20070194311. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a photoelectric transducer used for a dye-sensitized solar cell and the like. BACKGROUND ART [0002] A dye-sensitized solar cell of a new type reported in a journal "Nature" in 1991 by Graetzel et al. received attention as exhibiting a remarkably high conversion efficiency (on the order of 7%) compared with conventional dye-sensitized solar cells. A dye-sensitized solar cell realizes a photoelectric conversion by injecting excited electrons generated by a dye that has collected light to a semiconductor. Thus, it is important that a large amount of sensitizing dye is carried on a semiconductor so as to enhance a light collecting ability, and electrons are injected to a semiconductor as fast as possible from the sensitizing dye. The new dye-sensitized solar cell that also is called a Graetzel cell solves this problem by allowing a porous film made of titanium oxide of ultrafine particles to carry a ruthenium complex that is a sensitizing dye. [0003] The Graetzel cell can be assembled merely by coating a transparent electrode with a paste in which ultrafine particles of titanium oxide are dispersed, allowing the transparent electrode to carry a sensitizing dye, and filling an electrolyte between the transparent electrode and a counter electrode. Compared with conventional solar cells, the Graetzel cell can be produced with a simple apparatus, so that it receives attention as one of the next generation solar cells. [0004] A major feature of the Graetzel cell is to use a porous semiconductor film obtained by sintering titanium oxide of ultrafine particles. The purpose of sintering titanium oxide is to allow ultrafine particles of a semiconductor to bind each other, and to ensure a conducting path for optically excited electrons injected from a sensitizing dye. Usually, the sintering temperature of titanium oxide for ensuring a conducting path for optically excited electrons is in a range of 450.degree. C. to 550.degree. C. When the sintering temperature is less than this range, the binding between the ultrafine particles of a semiconductor becomes insufficient. Because of this, unless a material having a softening temperature higher than the sintering temperature is selected as a substrate of a transparent electrode for forming a porous titanium oxide film, the transparent electrode actually cannot be used. However, most of the materials having light transparency have a softening temperature lower than the sintering temperature of titanium oxide. Therefore, it is difficult to use such a material as an electrode substrate of the Graetzel cell. [0005] Furthermore, when a film is used as a substrate of the Graetzel cell, for example, a roll-to-roll continuous manufacturing process described in WO 97/15959 and a production method suitable for mass-production described in WO 99/66519 can be adopted, and the Graetzel cell can be produced at a lower cost than the existing solar cells. Therefore, the film type Graetzel cell can be deployed for a very wide use. However, when a film is used as a substrate, a porous titanium oxide film made of ultrafine particles cannot handle the flexibility of the film, and becomes likely to crack or peel off. Furthermore, in WO 93/20569, a method for adding a surfactant "TRITON X-100" of a nonionic type to a titanium oxide paste for the purpose of reducing cracking of a coating film during coating of the titanium oxide paste is described. In this method, as much as 40% by mass of "TRITON X-100" is added to titanium oxide, which may inhibit the transfer of electrons in a titanium oxide film. [0006] Furthermore, in WO 00/72373, by applying a pressure of 100 to 1000 kg/cm.sup.2 to a titanium oxide film, the mechanical strength and electron conducting path of the titanium oxide film are ensured without sintering titanium oxide. This technique is characterized in that a binder is not contained in a titanium oxide film so as to avoid the inhibition of electron transfer in a titanium oxide film by a binder. [0007] On the other hand, the inventors of the present invention confirmed that a titanium oxide film with mechanical strength to some degree can be obtained by applying a large pressure to the titanium oxide film. However, the film thus obtained has weak adhesion with respect to a substrate, and the titanium oxide film is likely to peel off. DISCLOSURE OF INVENTION [0008] A photoelectric transducer of the present invention includes: a first electrode with a semiconductor layer carrying a sensitizing dye formed thereon; a second electrode opposed to the semiconductor layer of the first electrode; and an electrolyte layer placed between the semiconductor layer of the first electrode and the second electrode. The semiconductor layer contains semiconductor particles and a binder, and a porosity of the semiconductor layer is in a range of 40 to 80%. [0009] Furthermore, a method for producing a photoelectric transducer of the present invention includes: a first electrode with a semiconductor layer carrying a sensitizing dye formed thereon; a second electrode opposed to the semiconductor layer of the first electrode; and an electrolyte layer placed between the semiconductor layer of the first electrode and the second electrode. A solution containing semiconductor particles and a binder is applied to the first electrode and dried, and then, pressed with a pressure of 20 to 200 MPa, whereby the semiconductor layer is formed. BRIEF DESCRIPTION OF DRAWINGS [0010] FIG. 1 is a schematic cross-sectional view showing an exemplary photoelectric transducer of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION [0011] The present invention can solve the conventional problems, and provides a photoelectric transducer exhibiting excellent photoelectric conversion characteristics, using a semiconductor layer with strong adhesion capable of ensuring a conducting path for optically excited electrons without being sintered at a high temperature and handling the flexibility of a substrate, and a method for producing the photoelectric transducer. Hereinafter, the embodiments of the present invention will be described. [0012] An exemplary photoelectric transducer of the present invention includes: a first electrode with a semiconductor layer carrying a sensitizing dye formed thereon; a second electrode opposed to the semiconductor layer of the first electrode; and an electrolyte layer placed between the semiconductor layer of the first electrode and the second electrode. The semiconductor layer contains semiconductor particles and a binder, and a porosity of the semiconductor layer is in a range of 40 to 80%. [0013] Since the semiconductor layer contains semiconductor particles and a binder, a semiconductor layer with strong adhesion capable of handling the flexibility of a substrate can be realized. Furthermore, due to the porosity of the semiconductor layer in a range of 40 to 80%, a conducting path for optically excited electrons can be ensured even without sintering the semiconductor layer at a high temperature, whereby a conversion efficiency can be enhanced. [0014] Furthermore, in the photoelectric transducer of one embodiment, it is preferable that a ratio of the binder contained in the semiconductor layer is in a range of 0.2 to 10% by mass with respect to a total component forming the semiconductor layer. This is because a conversion efficiency is enhanced further in this range. [0015] Furthermore, in the photoelectric transducer of one embodiment, it is preferable that the binder contains at least one selected from the group consisting of a cellulose derivative, a rubber elastic polymer, a single polymer or a copolymer of N-vinylacetamide, polyethylene oxide, sodium alginate, polyacrylic acid and its salt, polyvinylphenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrolidone, polyacrylamide, polyhydroxy(meth)acrylate, polyvinyl acetal, a styrene-maleic acid copolymer, polyethylene glycol, starch oxide, phosphorylated starch, casein, and polyolefin. These materials have strong adhesion and are sufficiently flexible, so that a semiconductor layer capable of handling the flexibility of a substrate more pliably can be realized. [0016] Furthermore, in the photoelectric transducer of one embodiment, it is preferable that the first electrode is configured with an electrode portion adhering to a synthetic resin film. According to this, electrodes can be mass-produced easily, resulting in a reduction in a production cost. [0017] Furthermore, in the photoelectric transducer of one embodiment, it is preferable that the synthetic resin film is at least one selected from the group consisting of a polyethylene terephthalate film, a polyethylene naphthalate film, a polyether sulphone film, a polyarylate film, a polyimide film, a cycloolefin polymer film, and a norbornene resin film. This is because these films are excellent in stiffness and heat resistance. [0018] Furthermore, an exemplary method for producing a photoelectric transducer of the present invention includes: a first electrode with a semiconductor layer carrying a sensitizing dye formed thereon; a second electrode opposed to the semiconductor layer of the first electrode; and an electrolyte layer placed between the semiconductor layer of the first electrode and the second electrode. A solution containing semiconductor particles and a binder is applied to the first electrode and dried, and then, pressed with a pressure of 20 to 200 MPa, whereby the semiconductor layer is formed. [0019] According to the above, the semiconductor layer is formed by coating the first electrode with a solution containing semiconductor particles and a binder, followed by drying, and pressing the resultant electrode with a pressure of 20 to 200 MPa. Therefore, a semiconductor layer can be formed, which is capable of ensuring a conducting path for optically excited electrons even without being sintered at a high temperature, and handling the flexibility of a substrate. Continue reading... Full patent description for Photoelectric transducer and its manufacturing method Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Photoelectric transducer and its manufacturing method patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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